Integrated circuits are used for a wide variety of purposes in the semiconductor industry, and many different electrical components of integrated circuits are combined or utilized for various applications. For example, integrated circuits are used for several different types of memory systems. Many memory systems in microelectronics use an array to select a specific memory cell to read. The memory array may include a plurality of bitlines and a plurality of wordlines, where each bitline intersects each wordline, and the memory cell is located at the intersection point. The information stored in memory can be accessed by reading the state of the memory cell at a selected bitline and wordline. For example, a simple grid may have 8 bitlines and 8 wordlines, for a total of 64 memory cells. Each individual memory cell may be designated and selected by activating the associated bitline and wordline.
The memory cell located at a bitline and wordline intersection may have two different states, which represent a zero (0) or a one (1) in a binary number system. The integrated circuit may be configured to recognize the different states of cells, and associate the two different states with either a 0 or a 1. Therefore, an integrated circuit may use a wide variety of different types of memory cells including: circuits which are open or closed; capacitors which are charged or uncharged; variable resistors which have a high resistance or a low resistance; etc.
A programmable electrical connection is an electrical connection that can be set or changed between two or more different states. In some embodiments, the electrical connection may include a fuse or anti-fuse, where the electrical connection is either effectively complete (short) or broken (open) depending on the state of the fuse or anti-fuse. In other embodiments, the electrical connection includes a programmable layer with a variable resistance, so the electrical connection functions as a variable resistor.
Certain materials may be configured or used as anti-fuses, where essentially no current is allowed to flow (i.e. “open” state) until a programming voltage is applied to set the anti-fuse to be conductive. Some materials or structures may be configured to change between a low and high resistance state, where the resistance state is changed by applying a set or reset voltage. For example, hafnium oxide can be reliably changed between different resistance states. These “programmable” materials may be used as components of a memory cell, or for other purposes as well, such as controlling current to selected components. The creation of a fuse or anti-fuse typically requires the deposition of several layers with different compositions, and each layer typically requires at least one additional manufacturing step, such as removal of excess materials, application of photoresist layers, etc.
There is market pressure to reduce the size, cost, and power consumption of integrated circuits while increasing the speed of operation and the reliability of the components. Many integrated circuits are used for memory purposes, so the market pressures also apply to integrated circuits used for memory. Processes and methods that eliminate manufacturing steps by utilizing existing structures can lower cost and may reduce the size of various components. There is also pressure to increase the availability of small, low cost, fast memory that is non-volatile on chip, which means the integrated circuit retains the saved memory cell states when powered down.
Accordingly, it is desirable to develop new programmable electrical connections for use in integrated circuits that reduce size and cost while being reliable. In addition, it is desirable to develop methods and systems for incorporating programmable electrical connections into memory cells for improved non-volatile performance. Furthermore, other desirable features and characteristics of the present embodiment will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.